If SHARED_SERVERS is greater than 0, then DISPATCHERS defaults to '(PROTOCOL=tcp)', causing 1 TCP/IP dispatcher to be created.

Modifiable

ALTER SYSTEM

Basic

No

DISPATCHERS configures dispatcher processes in the shared server architecture. The parsing software supports a name-value syntax to enable the specification of attributes in a position-independent, case-insensitive manner. For example:

DISPATCHERS = '(PROTOCOL=TCP)(DISPATCHERS=3)'

Attributes may be specified using the full attribute name or any substring beginning with the first 3 characters. For example, SESSIONS can be specified as SES, SESS, SESSI, and so on.

Specify only one of the following attributes: PROTOCOL, ADDRESS, or DESCRIPTION. If you specify either ADDRESS or DESCRIPTION, then you can specify additional network attributes. Doing so supports multi-homed hosts.

dispatch_clause

PROTOCOL

The network protocol for which the dispatcher generates a listening endpoint.

ADDRESS

The network protocol address of the endpoint on which the dispatchers listen.

DESCRIPTION

The network description of the endpoint on which the dispatchers listen, including the protocol address.

options_clause

DISPATCHERS

The initial number of dispatchers to start. The default is 1.

SESSIONS

The maximum number of network sessions to allow for each dispatcher. The default is operating system-specific. Most operating systems have a default of 16 KB.

CONNECTIONS

The maximum number of network connections to allow for each dispatcher. The default is operating system-specific.

TICKS

The length of a network tick in seconds. The default is 1 second.

POOL

Enables Connection Pooling.

An integer indicates that Connection Pooling is enabled for both incoming and outgoing network connections. The number specified is the timeout in ticks for both incoming and outgoing network connections.

ON, YES, TRUE, and BOTH indicate that Connection Pooling is enabled for both incoming and outgoing network connections. A default timeout of 10 ticks is used for both incoming and outgoing network connections.

IN indicates that Connection Pooling is enabled for incoming network connections and the default timeout of 10 ticks is used for incoming network connections.

OUT indicates that Connection Pooling is enabled for outgoing network connections and the default timeout of 10 ticks is used for outgoing network connections.

NO, OFF, and FALSE indicate that Connection Pooling is disabled for both incoming and outgoing network connections. This is the default.

POOL can also be assigned a name-value string such as: "(IN=10)", "(OUT=20)", or "(IN=10)(OUT=20)". In such cases:

If an IN numeric value is specified, then Connection Pooling is enabled for incoming connections, and the number specified is the timeout in ticks for incoming network connections.

If an OUT numeric value is specified, then Connection Pooling is enabled for outgoing network connections, and the number specified is the timeout in ticks for outgoing network connections.

If the numeric value of a specified timeout is 1, then the default value of 10 ticks is used. If the numeric value is 0, then pooling is not on.

MULTIPLEX

Enables the Oracle Connection Manager session multiplexing feature.

The values 1, ON, YES, TRUE, and BOTH indicate that Network Session Multiplex is enabled for both incoming and outgoing network connections.

The value IN indicates that Network Session Multiplex is enabled for incoming network connections.

The value OUT indicates that Network Session Multiplexing is enabled for outgoing network connections.

The values 0, NO, OFF, and FALSE indicate that Network Session Multiplexing is disabled for both incoming and outgoing network connections. This is the default.

LISTENER

Specifies the network name of an address or address list of the Oracle Net listeners with which the dispatchers will register.

The LISTENER attribute facilitates administration of multi-homed hosts. This attribute specifies the appropriate listeners with which the dispatchers will register. The LISTENER attribute takes precedence over the LOCAL_LISTENER and REMOTE_LISTENER parameters. See "LOCAL_LISTENER" and "REMOTE_LISTENER".

SERVICE

Specifies one or more names by which clients can connect to the dispatchers. The SERVICE attribute takes precedence over the SERVICE_NAMES parameter.

INDEX

Use this attribute in an ALTER SYSTEM SET DISPATCHERS statement to indicate which dispatcher configuration you want to modify. (If you specify INDEX in the initialization parameter file, the Oracle Database ignores it.) In an ALTER SYSTEM statement, INDEX specifies the order in which the parameter's values were initialized. The value ranges from 0 (for the first dispatcher configuration) to one less than the total number of dispatcher configurations you define.

For example, if you specify 3 dispatcher configurations in the initialization parameter file, you would modify the third dispatcher configuration by specifying INDEX=2 in the ALTER SYSTEM statement. You could also add an additional dispatcher configuration in the ALTER SYSTEM statement by specifying INDEX=3.

If INDEX is not specified in the ALTER SYSTEM statement, then the PROTOCOL, ADDRESS, or DESCRIPTION attributes must be specified, and if a dispatcher configuration matching this PROTOCOL, ADDRESS, or DESCRIPTION exists, then that configuration will be modified. Otherwise, a new configuration will be added.